U.S. patent number 11,158,651 [Application Number 16/773,103] was granted by the patent office on 2021-10-26 for vertical memory devices.
This patent grant is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. The grantee listed for this patent is SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Kohji Kanamori, Kwangsoo Kim, Taehun Kim, Yongseok Kim, Kyunghwan Lee.
United States Patent |
11,158,651 |
Lee , et al. |
October 26, 2021 |
Vertical memory devices
Abstract
A vertical memory device includes gate electrodes on a
substrate. The gate electrodes are spaced apart from each other in
a vertical direction. A channel penetrates the gate electrodes and
extends in the vertical direction. A tunnel insulation pattern is
formed on an outer sidewall of the channel. A charge trapping
pattern structure is formed on an outer sidewall of the tunnel
insulation pattern adjacent the gate electrodes in a horizontal
direction. The charge trapping pattern structure includes upper and
lower charge trapping patterns. A blocking pattern is formed
between the charge trapping pattern structure and each of the
adjacent gate electrodes. An upper surface of the upper charge
trapping pattern is higher than an upper surface of the adjacent
gate electrode. A lower surface of the lower charge trapping
pattern is lower than a lower surface of an adjacent gate
electrode.
Inventors: |
Lee; Kyunghwan (Hwaseong-si,
KR), Kim; Kwangsoo (Hwaseong-si, KR), Kim;
Taehun (Gwacheon-si, KR), Kim; Yongseok
(Suwon-si, KR), Kanamori; Kohji (Seongnam-si,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRONICS CO., LTD. |
Suwon-si |
N/A |
KR |
|
|
Assignee: |
SAMSUNG ELECTRONICS CO., LTD.
(Suwon-si, KR)
|
Family
ID: |
73650270 |
Appl.
No.: |
16/773,103 |
Filed: |
January 27, 2020 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200388632 A1 |
Dec 10, 2020 |
|
Foreign Application Priority Data
|
|
|
|
|
Jun 10, 2019 [KR] |
|
|
10-2019-0067767 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G11C
5/02 (20130101); H01L 27/11565 (20130101); H01L
29/40117 (20190801); H01L 29/7926 (20130101); G11C
16/0466 (20130101); H01L 27/11582 (20130101); G11C
16/0483 (20130101) |
Current International
Class: |
H01L
29/792 (20060101); G11C 5/02 (20060101); H01L
27/11582 (20170101); G11C 16/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Oh; Jaehwan
Attorney, Agent or Firm: F. Chau & Associates, LLC
Claims
What is claimed is:
1. A vertical memory device, comprising: gate electrodes on a
substrate, the gate electrodes spaced apart from each other in a
vertical direction that is substantially perpendicular to an upper
surface of the substrate; a channel penetrating the gate electrodes
and extending in the vertical direction; a tunnel insulation
pattern formed on an outer sidewall of the channel; a charge
trapping pattern structure formed on an outer sidewall of the
tunnel insulation pattern adjacent the gate electrodes in a
horizontal direction that is substantially parallel to the upper
surface of the substrate, the charge trapping pattern structure
including upper and lower charge trapping patterns; and a blocking
pattern formed between the charge trapping pattern structure and
each of the gate electrodes adjacent to the charge trapping pattern
structure, wherein an upper surface of the upper charge trapping
pattern is higher than an upper surface of a gate electrode
adjacent to the charge trapping pattern structure, and wherein a
lower surface of the lower charge trapping pattern is lower than a
lower surface of a gate electrode adjacent to the charge trapping
structure.
2. The vertical memory device of claim 1, wherein a thickness of
the upper charge trapping pattern in the horizontal direction
decreases from a top portion toward a bottom portion and a
thickness of the lower charge trapping pattern in the horizontal
direction increases from a top portion toward a bottom portion.
3. The vertical memory device of claim 1, wherein the blocking
pattern covers the upper surface and the lower surface of each of
the gate electrodes.
4. The vertical memory device of claim 1, wherein: the blocking
pattern is a second blocking pattern; and the vertical memory
device further includes a first blocking pattern covering the upper
surface of the upper charge trapping pattern and the lower surface
of the lower charge trapping pattern.
5. The vertical memory device of claim 4, wherein the second
blocking pattern has a thickness in the vertical direction that is
greater than a thickness of the first blocking pattern.
6. The vertical memory device of claim 1, wherein: the upper and
lower charge trapping patterns are spaced apart from each other in
the vertical direction by a portion of the tunnel insulation
pattern; and the tunnel insulation pattern includes a protrusion
that protrudes from the channel in the horizontal direction.
7. The vertical memory device of claim 6, wherein the blocking
pattern contacts the protrusion of the tunnel insulation pattern,
and has a convex shape toward each of the gate electrodes.
8. The vertical memory device of claim 1, wherein a sidewall of
each of the gate electrodes that is adjacent to the channel in the
horizontal direction has a concave shape or a convex shape toward
the channel.
9. The vertical memory device of claim 1, wherein a sidewall of
each of the gate electrodes that is adjacent to the channel in the
horizontal direction has a wave shape toward the channel.
10. A vertical memory device, comprising: gate electrodes on a
substrate, the gate electrodes spaced apart from each other in a
vertical direction that is substantially perpendicular to an upper
surface of the substrate; a channel penetrating the gate electrodes
and extending in the vertical direction; a tunnel insulation
pattern formed on an outer sidewall of the channel; a charge
trapping pattern structure formed on an outer sidewall of the
tunnel insulation pattern adjacent the gate electrodes in a
horizontal direction that is substantially parallel to the upper
surface of the substrate, the charge trapping pattern structure
including upper and lower charge trapping patterns; and a blocking
pattern formed between the charge trapping pattern structure and
each of the gate electrodes adjacent to the charge trapping pattern
structure, wherein the blocking pattern covers an upper surface and
a lower surface of each of the gate electrodes.
11. The vertical memory device of claim 10, wherein the blocking
pattern covers an upper surface of the upper charge trapping
pattern and a lower surface of the lower charge trapping
pattern.
12. The vertical memory device of claim 11, wherein a portion of
the blocking pattern covering the upper surface and the lower
surface of each of the gate electrodes has a thickness that is
greater than a thickness of a portion of the blocking pattern
covering the upper surface of the upper charge trapping pattern and
the lower surface of the lower charge trapping pattern.
13. The vertical memory device of claim 10, wherein a thickness of
the upper charge trapping pattern in the horizontal direction
decreases from a top portion toward a bottom portion, and a
thickness of the lower charge trapping pattern in the horizontal
direction increases from a top portion toward a bottom portion.
14. The vertical memory device of claim 10, wherein the tunnel
insulation pattern includes a protrusion that protrudes in the
horizontal direction, wherein the upper and lower charge trapping
patterns are spaced apart from each other in the vertical direction
by the protrusion.
15. The vertical memory device of claim 14, wherein the blocking
pattern contacts the protrusion of the tunnel insulation pattern,
and has a convex shape toward each of the gate electrodes.
16. A vertical memory device, comprising: gate electrodes on a
substrate, the gate electrodes spaced apart from each other in a
vertical direction that is substantially perpendicular to an upper
surface of the substrate; a channel penetrating the gate electrodes
and extending in the vertical direction; a tunnel insulation
pattern formed on an outer sidewall of the channel, the tunnel
insulation pattern including a protrusion that protrudes in a
horizontal direction that is substantially parallel to the upper
surface of the substrate; a charge trapping pattern structure
formed on an outer sidewall of the tunnel insulation pattern that
is adjacent the gate electrodes in the horizontal direction, the
charge trapping pattern structure including upper and lower charge
trapping patterns that are spaced apart from each other in the
vertical direction by the protrusion of the tunnel insulation
pattern; and a blocking pattern having a concave shape toward each
of the gate electrodes, the concave shape corresponding to the
protrusion of the tunnel insulation pattern.
17. The vertical memory device of claim 16, wherein a thickness of
the upper charge trapping pattern in the horizontal direction
decreases from a top portion toward a bottom portion, and a
thickness of the lower charge trapping pattern in the horizontal
direction increases from a top portion toward a bottom portion.
18. The vertical memory device of claim 16, wherein the blocking
pattern covers an upper surface and a lower surface of each of the
gate electrodes.
19. The vertical memory device of claim 18, wherein the blocking
pattern covers an upper surface of the upper charge trapping
pattern and a lower surface of the lower charge trapping
pattern.
20. The vertical memory device of claim 19, wherein a portion of
the blocking pattern covering the upper surface and the lower
surface of each of the gate electrodes has a thickness that is
greater than a thickness of a portion of the blocking pattern
covering the upper surface of the upper charge trapping pattern and
the lower surface of the lower charge trapping pattern.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority under 35 USC .sctn. 119 to Korean
Patent Application No. 10-2019-0067767, filed on Jun. 10, 2019 in
the Korean Intellectual Property Office (KIPO), the disclosure of
which is incorporated by reference in its entirety herein.
TECHNICAL FIELD
The present inventive concepts relate to vertical memory devices.
More particularly, the present inventive concepts relate to
vertical memory devices having vertical channels.
DISCUSSION OF RELATED ART
To increase the degree of integration of a vertical memory device,
the size of each layer that is vertically stacked in the device may
be reduced. However, there may be a process limit in scaling down
the vertical memory device beyond a certain level.
SUMMARY
Exemplary embodiments of the present inventive concepts provide
vertical memory devices having improved electrical
characteristics.
According to an exemplary embodiment of the present inventive
concepts, a vertical memory device includes gate electrodes on a
substrate. The gate electrodes are spaced apart from each other in
a vertical direction that is substantially perpendicular to an
upper surface of the substrate. A channel penetrates the gate
electrodes and extends in the vertical direction. A tunnel
insulation pattern is formed on an outer sidewall of the channel. A
charge trapping pattern structure is formed on an outer sidewall of
the tunnel insulation pattern adjacent the gate electrodes in a
horizontal direction that is substantially parallel to the upper
surface of the substrate. The charge trapping pattern structure
includes upper and lower charge trapping patterns. A blocking
pattern is formed between the charge trapping pattern structure and
each of the gate electrodes are adjacent to the blocking pattern.
An upper surface of the upper charge trapping pattern is higher
than an upper surface of a gate electrode adjacent to the charge
trapping pattern structure. A lower surface of the lower charge
trapping pattern is lower than a lower surface of a gate electrode
adjacent to the charge trapping structure.
According to an exemplary embodiment of the present inventive
concepts, a vertical memory device includes gate electrodes on a
substrate. The gate electrodes are spaced apart from each other in
a vertical direction that is substantially perpendicular to an
upper surface of the substrate. A channel penetrates the gate
electrodes and extends in the vertical direction. A tunnel
insulation pattern is formed on an outer sidewall of the channel. A
charge trapping pattern structure is formed on an outer sidewall of
the tunnel insulation pattern adjacent the gate electrodes in a
horizontal direction that is substantially parallel to the upper
surface of the substrate. The charge trapping pattern structure
includes upper and lower charge trapping patterns. A blocking
pattern is formed between the charge trapping pattern structure and
each of the gate electrodes are adjacent to the blocking pattern.
The blocking pattern covers an upper surface and a lower surface of
each of the gate electrodes.
According to an exemplary embodiment, a vertical memory device
includes gate electrodes on a substrate. The gate electrodes are
spaced apart from each other in a vertical direction that is
substantially perpendicular to an upper surface of the substrate. A
channel penetrates the gate electrodes and extends in the vertical
direction. A tunnel insulation pattern is formed on an outer
sidewall of the channel. The tunnel insulation pattern includes a
protrusion that protrudes in a horizontal direction that is
substantially parallel to the upper surface of the substrate. A
charge trapping pattern structure is formed on an outer sidewall of
the tunnel insulation pattern that is adjacent the gate electrodes
in the horizontal direction. The charge trapping pattern structure
includes upper and lower charge trapping patterns that are spaced
apart from each other in the vertical direction by the protrusion
of the tunnel insulation pattern. A blocking pattern has a concave
shape toward each of the gate electrodes. The concave shape
corresponds to the protrusion of the tunnel insulation pattern.
A vertical memory device in accordance with exemplary embodiments
of the present inventive concepts may include a tunnel insulation
pattern, a charge trapping pattern structure, and a blocking
pattern sequentially formed on an outer sidewall of a channel that
extends through gate electrodes and insulation patterns alternately
and repeatedly formed in a vertical direction substantially
perpendicular to an upper surface of a substrate, and the charge
trapping pattern structure may include upper and lower charge
trapping patterns spaced apart from each other in the vertical
direction.
Accordingly, a plurality of charge trapping patterns may be
arranged in one transistor, so that the integration degree of the
vertical memory device including the transistor may be improved,
and electrons may be efficiently injected through the plurality of
charge trapping patterns, so that the electrical characteristic of
the vertical memory device may be improved.
BRIEF DESCRIPTION OF TIE DRAWINGS
FIG. 1 is a plan view illustrating a vertical memory device in
accordance with an exemplary embodiment of the present inventive
concepts.
FIG. 2 is a cross-sectional view taken along line A-A' of FIG. 1
illustrating a vertical memory device in accordance with an
exemplary embodiment of the present inventive concepts.
FIG. 3 is an enlarged cross-sectional view of region X in FIG. 2 in
accordance with an exemplary embodiment of the present inventive
concepts.
FIGS. 4-7, 9, 11, 13, 14, 16, 18 and 20 are cross-sectional views
taken along line A-A' of FIG. 1 illustrating stages of a method of
manufacturing a vertical memory device in accordance with exemplary
embodiments of the present inventive concepts.
FIGS. 8, 10, 12, 15, 17, 19 and 21 are enlarged cross-sectional
views illustrating stages of a method of manufacturing a vertical
memory device in accordance with exemplary embodiments of the
present inventive concepts.
FIGS. 22-24 are cross-sectional views taken along line A-A' of FIG.
1, illustrating stages of a method of manufacturing a vertical
memory device in accordance with exemplary embodiments of the
present inventive concepts.
FIGS. 25-29 are enlarged cross-sectional views illustrating stages
of a method of manufacturing a vertical memory device in accordance
with exemplary embodiments of the present inventive concepts.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Vertical memory devices and methods of manufacturing the same in
accordance with exemplary embodiments of the present inventive
concepts will be described more fully hereinafter with reference to
the accompanying drawings.
FIG. 1 is a plan view illustrating a vertical memory device in
accordance with an exemplary embodiment of the present inventive
concepts. FIG. 2 is a cross-sectional view taken along a line A-A'
of FIG. 1 illustrating a vertical memory device in accordance with
an exemplary embodiment of the present inventive concepts. FIG. 3
is an enlarged cross-sectional view of a region X in FIG. 2 in
accordance with an exemplary embodiment of the present inventive
concepts.
Hereinafter, a vertical direction substantially perpendicular to an
upper surface of a substrate is defined as a first direction, and
two directions intersecting with each other among horizontal
directions substantially parallel to the upper surface of the
substrate are defined as second and third directions, respectively.
As shown in the exemplary embodiment of FIG. 1, the second
direction and third direction may be orthogonal to each other.
Referring to FIGS. 1 to 3, the vertical memory device may include
insulation patterns 115, gate electrodes, a channel 225, a tunnel
insulation pattern 205, a charge trapping pattern structure 185,
and a first blocking pattern 177 on a substrate 100. The vertical
memory device may further include a semiconductor pattern 150, a
buried pattern 230, a pad 240, a second blocking pattern 285, a
second spacer 300, a common source line (CSL) 310, first to fourth
insulating interlayers 130, 250, 320 and 340, a contact plug 330,
and a bit line 350.
In an exemplary embodiment, the substrate 100 may include silicon,
germanium, silicon-germanium or III-V compounds such as GaP, GaAs,
GaSb, etc. In some exemplary embodiments, the substrate 100 may be
a silicon-on-insulator (SOI) substrate or a germanium-on-insulator
(GOI) substrate. However, exemplary embodiments of the present
inventive concepts are not limited thereto.
The insulation patterns 115 may be formed on a plurality of levels
along the first direction, and may be spaced apart from each other.
For example, the insulation patterns may have different distances
in the first direction between an upper surface of the substrate
100 and a bottom surface of the insulation pattern and such
distances may be referred to as levels. The insulation patterns 115
may have different thicknesses along the first direction depending
on the formed levels. For example, the insulation pattern 115
formed on a lowermost level from atop surface of the substrate 100
along the first direction may have the smallest thickness. The
insulation pattern 115 formed on a second level from the top
surface of the substrate may have the greatest thickness. The
uppermost insulation pattern 115 formed on an uppermost level
(e.g., the eight insulating pattern of FIG. 2 which has the
greatest distance between the bottom surface of the insulation
pattern and the top surface of the substrate in the first
direction) may have the second greatest thickness. Each of the
insulation patterns 115 formed on remaining middle levels between
the insulation pattern 115 formed on the uppermost level and the
insulation pattern formed on the lowermost level (e.g., the second
to seventh insulation patterns shown in the exemplary embodiment of
FIG. 2) may have a third greatest thickness. The insulation
patterns on the middle levels may have a substantially similar
thickness (e.g., length in the first direction). However, exemplary
embodiments of the present inventive concepts are not limited
thereto and the thicknesses of the insulation patterns may have
different arrangements in other exemplary embodiments. Furthermore,
the number of insulation patterns in the exemplary embodiment of
FIG. 2 is not limiting and may vary in other exemplary
embodiments.
Each of the gate electrodes may be formed between the insulation
patterns 115 (e.g., in the third direction). The gate electrodes
may be formed on a plurality of levels and are spaced apart from
each other (e.g., in the first direction). For example, as shown in
the exemplary embodiment of FIG. 2, the insulation patterns 115 and
the gate electrodes may be alternately and repeatedly stacked in
the first direction on the substrate 100. Each of the gate
electrodes may extend in the second direction, and a plurality of
gate electrodes may be arranged in the third direction and may be
spaced apart from each other. Each of the gate electrodes extending
in the second direction may be spaced apart from each other in the
third direction by a second spacer 300 and the CSL 310 formed in a
second opening 260.
The gate electrodes may include first to third gate electrodes 293,
295 and 297 sequentially formed along the first direction. In an
exemplary embodiment, the first gate electrode 293 may serve as a
ground selection line (GSL), the second gate electrodes 295 may
serve as a word line, and the third gate electrode 297 may serve as
a string selection line (SSL). Each of the first to third gate
electrodes 293, 295 and 297 may be formed on one level or a
plurality of levels. Furthermore, one or more dummy word lines may
be further formed between the first and second gate electrodes 293
and 295 and/or between the second and third gate electrodes 295 and
297.
In the exemplary embodiment shown in FIG. 2, the first gate
electrode 293 may be formed on a lowermost level (e.g., the
smallest distance between the bottom surface of the electrode and
an upper surface of the substrate 100 in the first direction), the
third gate electrode 297 may be formed on an uppermost level and
one level thereunder, and the second gate electrode 295 may be
formed on a plurality of levels between the first gate electrode
293 and the third gate electrode 297 (e.g., the second to fifth
levels in the exemplary embodiment of FIG. 2). Accordingly, the
first gate electrode 293 may be formed adjacent to the
semiconductor pattern 150 (e.g., in the third direction), and each
of the second and third gate electrodes 295 and 297 may be formed
adjacent to the channel 225 (e.g., in the third direction).
In an exemplary embodiment, the first gate electrode 293 may
include a first gate conductive pattern and a first gate barrier
pattern covering upper and lower surfaces (e.g., in the first
direction) of the first gate conductive pattern and a portion of a
sidewall of the first gate conductive pattern. The second gate
electrode 295 may include a second gate conductive pattern and a
second gate barrier pattern covering upper and lower surfaces
(e.g., in the first direction) of the second gate conductive
pattern and a portion of a sidewall of the second gate conductive
pattern. The third gate electrode 297 may include a third gate
conductive pattern and a third gate barrier pattern covering upper
and lower surfaces (e.g., in the first direction) of the third gate
conductive pattern and a portion of a sidewall of the third gate
conductive pattern.
The upper surface, the lower surface and the sidewall adjacent to
the channel 225 of each of the gate electrodes may be covered by
the second blocking pattern 285. The second blocking pattern 285
may also cover a portion of a sidewall of each of the insulation
patterns 115, a sidewall of each of the first and second insulating
interlayers 130 and 250, and a portion of the upper surface of the
substrate 100.
In an exemplary embodiment, the sidewall of each of the second and
third gate electrodes 295 and 297 closest to the channel (e.g., and
opposing the channel) in the third direction may have a concave
shape or a convex shape toward the channel 225 as a whole.
The channel 225 may extend in the first direction on the
semiconductor pattern 150 formed on the upper surface of the
substrate 100, and may extend through the insulation patterns 115,
and the second and third gate electrodes 295 and 297 alternately
and repeatedly stacked.
In an exemplary embodiment, the semiconductor pattern 150 may have
a pillar shape, e.g., a cylindrical shape.
In an exemplary embodiment, the semiconductor pattern 150 may be
formed such that an upper surface thereof is positioned in the
first direction between an upper surface and a lower surface of the
insulation pattern 115 formed on the second level that has the
greatest thickness among the insulation patterns 115.
The channel 225 may extend through the insulation patterns 115
formed on the first gate electrode 293, and the second and third
gate electrodes 295 and 297. In an exemplary embodiment, the
channel 225 may have a cup shape, and an inner space of the cup
shape may be filled with the buried pattern 230 having a pillar
shape. Alternatively, the channel 225 may have a pillar shape, and
the buried pattern 230 may not be formed.
A plurality of channels 225 may be formed in the second and third
directions, and thus a channel array may be defined.
The tunnel insulation pattern 205 may have a cup shape having a
central portion that surrounds an outer sidewall of the channel 225
and extends in the first direction and is penetrated. In an
exemplary embodiment, an inner sidewall (e.g., adjacent the channel
225) and an outer sidewall (e.g., closest to the electrodes and
insulation pattern 115) of a portion of the tunnel insulation
pattern 205 formed between each of the insulation patterns 115 and
the channel 225 may have a vertical slope (e.g., perpendicular)
with respect to the upper surface of the substrate 100. However, in
an exemplary embodiment, an inner sidewall and an outer sidewall of
a portion of the tunnel insulation pattern 205 formed between each
of the first to third gate electrodes 293, 295 and 297 and the
channel 225 may at least partially have a slope that is not
vertical (e.g., extending in the third direction D3), but varies
with respect to the upper surface of the substrate 100.
The charge trapping pattern structure 185 including upper and lower
charge trapping patterns 185a and 185b may be formed between the
second blocking pattern 285 that covers an outer sidewall of the
tunnel insulation pattern 205 and the sidewall of each of the gate
electrodes. The first blocking pattern 177 having a thin thickness
may be formed between the charge trapping pattern structure 185 and
the insulation patterns 115 formed thereon and thereunder (e.g., in
the first direction). In one exemplary embodiment, the outer
sidewall of the tunnel insulation pattern 205 may further protrude
from an outer sidewall of each of the upper and lower charge
trapping patterns 185a and 185b in the third direction toward the
gate electrode. For example, as shown in the exemplary embodiment
of FIG. 2, the middle portion of the tunnel insulation pattern 205
(e.g., in the first direction) may protrude from the outer
sidewall.
In exemplary embodiments, the lowermost first blocking pattern in
the first direction may partially cover a surface of the insulation
pattern 115 that has the greatest thickness on the second level and
the upper surface of the semiconductor pattern 150. The uppermost
first blocking pattern 177 in the first direction may partially
cover a surface of the insulation pattern 115 that has the second
greatest thickness on the uppermost level and a lower surface of
the pad 240. The remaining first blocking patterns 177 may
partially cover surfaces of the insulation patterns 115 on the
remaining levels. For example, the first blocking patterns 177 may
cover an outer sidewall of the insulation patterns 115 which extend
in the first direction and a portion of the top and bottom surfaces
of the insulation patterns adjacent thereto.
Each of the upper and lower charge trapping patterns 185a and 185b
may have a sidewall that is not vertical (e.g., perpendicular), but
varies (e.g., extends in the third direction) with respect to the
upper surface of the substrate 100. Each of the upper and lower
charge trapping patterns 185a and 185b may have a symmetrical shape
along the first direction based on the outer sidewall of the tunnel
insulation pattern 205 protruded from the channel 225. In an
exemplary embodiment, an upper surface of the upper charge trapping
pattern 185a contacting the first blocking pattern 177 and a lower
surface of the lower charge trapping pattern 185b contacting the
first blocking pattern 177 may have substantially the same width in
the third direction.
In an exemplary embodiment, a thickness of the upper charge
trapping pattern 185a in the third direction may gradually increase
from the top toward the bottom, and a thickness of the lower charge
trapping pattern 185b in the third direction may gradually decrease
from the top toward the bottom.
In exemplary embodiments, the charge trapping pattern structure 185
may be disposed between the channel 225 and each of the second and
third gate electrodes 295 and 297 (e.g., in the third direction).
An outer sidewall of the upper charge trapping pattern 185a is
exposed by a gap 270 during its formation (see, e.g., FIG. 14) may
have a slope that gradually decreases toward the top, and an outer
sidewall of the lower charge trapping pattern 185b exposed by the
gap 270 during its formation may have a slope that gradually
decreases toward the bottom.
In an exemplary embodiment, the upper and lower charge trapping
patterns 185a and 185b may be formed on a space between each of the
second and third gate electrodes 295 and 297 and the channel 225
(e.g., in the third direction). As shown in FIG. 3, the exemplary
embodiment of the upper surface of the upper charge trapping
pattern 185a may be higher (e.g., in the first direction) than
upper surfaces of the second and third gate electrodes 295 and 297
adjacent thereto, and a lower surface of the lower charge trapping
pattern 185b may be lower than lower surfaces of the second and
third gate electrodes 295 and 297 adjacent thereto.
In an exemplary embodiment, the first blocking pattern 177 may
include an oxide, such as silicon oxide, and each of the upper and
lower charge trapping patterns 185a and 185b may include a nitride,
such as silicon nitride. However, exemplary embodiments of the
present inventive concepts are not limited thereto.
The first insulating interlayer 130 may be formed on a first
structure that includes the charge trapping pattern structure 185,
the tunnel insulation pattern 205 and the channel 225, and the
uppermost insulation pattern 115 formed on the uppermost level, and
the pad 240 may extend through the first insulating interlayer 130
to contact an upper surface of the first structure. The second
insulating interlayer 250 may be formed on the first insulating
interlayer 130 and the pad 240.
The second spacer 300 may be formed on a sidewall of the second
opening 260 that extends through the insulation patterns 115 and
the first to third gate electrodes 293, 295 and 297 to expose the
upper surface of the substrate 100. The second spacer 300 may
extend in the second direction. The CSL 310 may fill a remaining
portion of the second opening 260.
The third insulating interlayer 320 may be formed on the second
insulating interlayer 250, the CSL 310, the second spacer 300 and
the second blocking pattern 285. The contact plug 330 may extend
through the second and third insulating interlayers 250 and 320 to
contact an upper surface of the contact plug 330. The bit line 350
may extend through the fourth insulating interlayer 340 to contact
an upper surface of the contact plug 330. In exemplary embodiments,
the bit line 350 may extend in the third direction, and a plurality
of bit lines may be formed along the second direction.
As described above, the charge trapping pattern structure 185
formed between each of the second to third gate electrodes 295 and
297 among the gate electrodes and the channel 225 may include the
upper and lower charge trapping patterns 185a and 185b spaced apart
from each other along the first direction. Accordingly, a plurality
of charge trapping patterns may be arranged in one transistor.
Therefore, the integration degree of the vertical memory device
including the transistor may be improved. Also, electrons may be
efficiently injected into the second to third gate electrodes 295
and 297 through each of the upper and lower charge trapping
patterns 185a and 185b. Accordingly, the electrical characteristics
of the vertical memory device may be improved.
Since the second to third gate electrodes 295 and 297 and the
insulation patterns 115 may be formed to have a concave-convex
shape in the first direction as a whole, the charge trapping
pattern structure 185 may be at least partially interposed between
the second to third gate electrodes 295 and 297 along the first
direction, so that the interference between neighboring second to
third gate electrodes 295 and 297 may be minimized. Therefore,
coupling between the second electrodes 295 serving as word lines
may be reduced.
FIGS. 4 to 21 are cross-sectional views illustrating stages of a
method of manufacturing a vertical memory device in accordance with
exemplary embodiments of the present inventive concepts. FIGS. 4-7,
9, 11, 13, 14, 16, 18, 20 and 22-24 are cross-sectional views taken
along the line A-A' of FIG. 1. FIGS. 8, 10, 12, 15, 17, 19, 21 and
25-29 are enlarged cross-sectional views of the region X of
corresponding cross-sectional views, respectively.
Referring to FIG. 4, insulation layers 110 and sacrificial layers
120 may be alternately and repeatedly stacked on a substrate 100
(e.g., in the first direction). Accordingly, a plurality of
insulation layers 110 and a plurality of sacrificial layers 120 may
be alternately stacked in the first direction. In the exemplary
embodiment shown in FIG. 4, eight levels of insulation layers 110
and seven levels of sacrificial layers 120 are alternately formed
on the substrate 100. However, exemplary embodiments of the present
inventive concepts are not limited thereto and the number of the
insulation layers 110 and the sacrificial layers 120 may be greater
or less than that shown in the exemplary embodiment of FIG. 4.
In an exemplary embodiment, the insulation layers 110 and the
sacrificial layers 120 may be formed by a chemical vapor deposition
(CVD) process, a plasma enhanced chemical vapor deposition (PECVD)
process, an atomic layer deposition (ALD) process, etc. In an
exemplary embodiment, a lowermost insulation layer 110 formed
directly on an upper surface of the substrate 100 may also be
formed by a thermal oxidation process on the upper surface of the
substrate 100.
The insulation layer 110 may include a silicon oxide, such as
PE-TEOS, HDP oxide PEOX, etc. The sacrificial layer 120 may include
a material having an etching selectivity with respect to the
insulation layer 110, such as a silicon nitride. However, exemplary
embodiments of the present inventive concepts are not limited
thereto and the insulation layer 110 and sacrificial layer 120 may
be formed of various other materials.
In exemplary embodiments, the lowermost insulation layer 110 formed
on a first level in the first direction from the upper surface of
the substrate 100 may have the smallest thickness (e.g., in the
first direction) as compared with the insulation layer 110 at the
other levels. An insulation layer 110 formed on a second level in
the first direction from the upper surface of the substrate 100 may
have the greatest thickness (e.g., in the first direction) as
compared with the insulation layers 110 at the other levels.
Referring to FIG. 5, after forming a first insulating interlayer
130 on an uppermost insulation layer 110, an etching process using
an etching mask may be performed to etch the first insulating
interlayer 130, the insulation layers 110 and the sacrificial
layers 120 thereunder. A channel hole 140 extending through the
first insulating interlayer 130, the insulation layers 110 and the
sacrificial layers 120 may be formed to expose the upper surface of
the substrate 100.
In an exemplary embodiment, the channel hole 140 may also partially
extend through an upper portion of the substrate 100.
A semiconductor pattern 150 may be formed to partially fill the
channel hole 140.
For example, in an exemplary embodiment, a selective epitaxial
growth (SEG) process may be performed which uses the upper surface
of the substrate 100 exposed by the channel hole 140 as a seed. The
SEG process forms the semiconductor pattern 150 that may fill a
lower portion of the channel hole 140. Accordingly, the
semiconductor pattern 150 may include single crystalline silicon or
single crystalline germanium according to the material of the
substrate 100, and may be doped with impurities.
In another exemplary embodiment, the semiconductor pattern 150 may
be formed by forming an amorphous silicon layer filling the channel
hole 140, and performing a laser epitaxial growth (LEG) process or
a solid phase epitaxy (SPE) process on the amorphous silicon
layer.
In an exemplary embodiment, an upper surface of the semiconductor
pattern 150 may be disposed between an upper surface and a lower
surface of the insulation layer 110 on the second level among the
insulation layers 110 (e.g., the second closest insulation layer in
the first direction to an upper surface of the substrate 100).
The semiconductor pattern 150 may serve as a channel similar to a
channel 225 (see FIG. 15) formed subsequently, and thus may be
referred to as a lower channel.
Referring to FIG. 6, sidewalls of the sacrificial layers 120
exposed by the channel hole 140 may be partially removed to form
first recesses 160.
In an exemplary embodiment, the first recesses 160 may be formed by
a dry etching process or a wet etching process.
In an exemplary embodiment, each of the first recesses 160 may be
formed by partially removing each of the sacrificial layers 120
while maintaining a portion of the sacrificial layers. The first
recesses 160 may have a depth in the third direction. Accordingly,
the insulation layers 110 and the sacrificial layers 120
alternately and repeatedly stacked may have a concave-convex shape
along the first direction as a whole.
In an exemplary embodiment, a first recess 160 may not be formed on
a lowermost sacrificial layer 120. The lowermost sacrificial layer
120 may include a sidewall covered by the semiconductor pattern 150
formed on the lower portion of the channel hole 140. For example,
as shown in the exemplary embodiment of FIG. 6, the semiconductor
pattern 150 may have relatively planar sidewalls extending in the
first direction and a constant width in the third direction at
portions adjacent to the sacrificial layer 120.
Referring to FIGS. 7 and 8, a first blocking layer 170 and a charge
trapping layer 180 may be sequentially formed on a sidewall of the
channel hole 140, an inner sidewall of each of the first recesses
160, the upper surface of the semiconductor pattern 150 and an
upper surface of the first insulating interlayer 130.
The first blocking layer 170 may be formed along surfaces of the
insulation layers 110 and the sacrificial layers 120 that are
alternately and repeatedly stacked, and a surface of the first
insulating interlayer 130. For example, the first blocking layer
170 may be formed to cover sidewalls of the insulation layers 110
and the sacrificial layers 120 which extend in the first direction
and a portion of the top and bottom surfaces of the insulation
layers and sacrificial layers adjacent thereto which extend in the
third direction. The first blocking layer 170 may be conformally
formed to cover the inner sidewall of each of the first recesses
160 and to have a very small thickness. As the insulation layers
110 and the sacrificial layers 120 alternately and repeatedly
stacked may have the concave-convex shape along the first direction
as a whole, the first blocking layer 170 may also have a
concave-convex shape along the first direction as a whole
corresponding thereto.
The charge trapping layer 180 may be formed on the first blocking
layer 170 and may be adjacent surfaces of the insulation layers 110
and the sacrificial layers 120 alternately and repeatedly stacked,
and may fill each of the first recesses 160. A sidewall of a
portion of the charge trapping layer 180 formed on the sidewall of
the channel hole 140 may have a slope generally perpendicular with
respect to the upper surface of the substrate 100 along the first
direction. However, the sidewall of a portion of the charge
trapping layer 180 may also have portions having a slope that is
not vertical (e.g., perpendicular), but varies (e.g., extends in
the third direction) with respect to the upper surface of the
substrate 100 and may correspond to the shape of each of the first
recesses 160. For example, in the exemplary embodiment shown in
FIG. 7, a portion of the charge trapping layer 180 corresponding to
a center portion of each of the first recesses 160 in the first
direction may have a concave shape toward the channel hole 140
(e.g., a convex shape toward the sacrificial layer 120).
In an exemplary embodiment, the first blocking layer 170 may have a
constant thickness, and each of the portions of the charge trapping
layer 180 formed adjacent a sidewall of each of the insulation
layers 110, the upper surface of the first insulating interlayer
130, and the upper surface of the semiconductor pattern 150 may
also have a constant thickness. However, a portion of the charge
trapping layer 180 adjacent to each of the first recesses 160 may
not have a constant thickness, and may have a greater thickness
than other portions thereof having the constant thicknesses.
The first blocking layer 170 may have an oxide, such as a silicon
oxide, and the charge trapping layer 180 may have a nitride, such
as a silicon nitride.
Referring to FIGS. 9 and 10, in an exemplary embodiment, the charge
trapping layer 180 may be removed by a wet etching process or a dry
etching process until a portion of the first blocking layer 170
formed on the sidewall of each of the insulation layers 110 may be
exposed and the charge trapping layer 180 may remain only in each
of the first recesses 160.
By performing the removing process, portions of the charge trapping
layer 180 having relatively small thicknesses, such as the portions
of the charge trapping layer 180 formed on the sidewall of each of
the insulation layers 110, the upper surface of the first
insulating interlayer 130, and the upper surface of the
semiconductor pattern 150 may be completely removed. The portions
of the charge trapping layer 180 having a relatively large
thicknesses, such as the portions of the charge trapping layer 180
adjacent to each of the first recesses 160 may not be completely
removed, but may partially remain. As the portion of the charge
trapping layer 180 adjacent to each of the first recesses 160 may
have a concave shape toward the channel hole 140, a second recess
190 having a concave shape toward the channel hole 140 may be
formed on a sidewall of the remaining charge trapping layer 180
after the removing process.
In an exemplary embodiment, a width of the remaining charge
trapping layer 180 in the third direction may vary along the first
direction, and may gradually increase in portions closer to the
adjacent insulation layers. For example, the portion in the middle
of the charge trapping layer 180 in the first direction may have
the smallest width in the third direction.
In the exemplary embodiment shown in FIGS. 9 and 10, the remaining
charge trapping layer 180 is not separated by the second recess 190
along the first direction. However, exemplary embodiments of the
present inventive concepts are not limited thereto. For example, in
other exemplary embodiments, the remaining charge trapping layer
180 may be separated by the second recess 190 along the first
direction and a surface of the first blocking layer 170 formed on
the sidewall of each of the sacrificial layers 120 may be exposed
by the second recess 190.
Referring to FIGS. 11 and 12, a tunnel insulation layer 200 and a
first spacer layer 210 may be sequentially formed on the surface of
the first blocking layer 170 and a surface of the charge trapping
layer 180.
Each of sidewalls of the tunnel insulation layer 200 and the first
spacer layer 210 may have a slope that is vertical (e.g.,
perpendicular) with respect to the upper surface of the substrate
100 along the first direction. However, each of sidewalls of
portions of the tunnel insulation layer 200 and the first spacer
layer 210 adjacent to the second recesses 190 may have a slope that
is not vertical and which may vary (e.g., extend in the third
direction) with respect to the upper surface of the substrate
100.
For example, in the exemplary embodiment shown in FIG. 11, the
portions of the tunnel insulation layer 200 and the first spacer
layer 210 adjacent to the second recesses 190 may have a concave
shape in the third direction toward the channel hole 140. For
example, the tunnel insulation layer 200 and the first spacer layer
210 adjacent to the second recesses 190 may have a convex shape in
the third direction toward the sacrificial layers 120. The portion
of the first spacer layer 210 may have a shape that is relatively
less concave than the concave portion of the tunnel insulation
layer 200.
In an exemplary embodiment, the tunnel insulation layer 200 may
include, silicon oxide, etc., and the first spacer layer 210 may
include, silicon nitride, etc.
Referring to FIG. 13, the first spacer layer 210 may be
anisotropically etched to form a first spacer that is formed only
on the sidewall of the channel hole and exposes the tunnel
insulation layer 200 under the first spacer layer 210. The tunnel
insulation layer 200 and the first blocking layer 170 may be etched
using the first spacer as an etching mask.
Accordingly, portions of the tunnel insulation layer 200 and the
first blocking layer 170 on the upper surface of the semiconductor
pattern 150, and portions of the tunnel insulation layer 200 and
the first blocking layer 170 on the upper surface of the first
insulating interlayer 130 may be removed, and an upper portion of
the semiconductor pattern 150 may also be partially removed.
The etching process may convert the tunnel insulation layer 200
into a tunnel insulation pattern 205, and the first blocking layer
170 may be converted into a preliminary first blocking pattern 175.
In an exemplary embodiment, each of the tunnel insulation pattern
205 and the preliminary first blocking pattern 175 may have a cup
shape in which a central portion is penetrated. The charge trapping
layer 180 may have a ring shape.
After removing the first spacer to expose the tunnel insulation
pattern 205, a channel layer may be formed on the exposed tunnel
insulation pattern 205, the semiconductor pattern 150 and the first
insulating interlayer 130. A buried layer may be formed on the
channel layer to sufficiently fill a remaining portion of the
channel holes 140.
In an exemplary embodiment, the channel layer may include
polysilicon doped or undoped with impurities, or amorphous silicon.
In an exemplary embodiment in which the channel layer includes
amorphous silicon, a laser epitaxial growth (LEG) process or a
solid phase epitaxy (SPE) process may be further performed to
convert amorphous silicon into crystalline silicon. The buried
layer may include an oxide, such as silicon oxide, etc.
The buried layer and the channel layer may be planarized until the
upper surface of the first insulating interlayer 130 may be
exposed. A buried pattern 230 filling the remaining portion of each
of the channel holes 140 may be formed, and the channel layer may
be converted into a channel 225.
Accordingly, the preliminary first blocking pattern 175, the tunnel
insulation pattern 205, the channel 225 and the buried pattern 230
may be sequentially stacked on the semiconductor pattern 150 in
each of the channel holes 140. Each of the preliminary first
blocking pattern 175 and the tunnel insulation pattern 205 may have
a cup shape in which a central portion is penetrated. The channel
225 may have a cup shape and the buried pattern 230 may have a
pillar shape.
A plurality of channels 225 may be formed in each of the second and
third directions to form a channel array.
A charge trapping layer 180 may be formed on a sidewall of each of
the sacrificial layers 120 adjacent to a sidewall of the channel
225 between the preliminary first blocking pattern 175 and the
tunnel insulation pattern 205. The preliminary first blocking
pattern 175, charge trapping layer 180, tunnel insulation pattern
205 and channel 225 may be spaced apart in the third direction.
The upper portions of the buried pattern 230, the channel 225, the
tunnel insulation pattern 205 and the preliminary first blocking
pattern 175 may be removed to form a trench, and a pad 240 may be
formed to fill the trench.
For example, after removing each of the upper portions of the
buried pattern 230, the channel 225, the tunnel insulation pattern
205 and the preliminary first blocking pattern 175 by an etch back
process to form the trench, a pad layer filling the trench may be
formed on the buried pattern 230, the channel 225, the tunnel
insulation pattern 205, the preliminary first blocking pattern 175
and the first insulating interlayer 130. An upper portion of the
pad layer may be planarized until the upper surface of the first
insulating interlayer 130 may be exposed to form the pad 240. In an
exemplary embodiment, the pad layer may include polysilicon doped
with impurities or amorphous silicon. In an exemplary embodiment in
which the pad layer includes amorphous silicon, a process for
crystallizing the pad layer may be further performed.
Referring to FIGS. 14 and 15, a second insulating interlayer 250 is
formed on the upper surfaces (e.g., in the first direction) of the
first insulating interlayer 130 and the pad 240. A second opening
260 extending through the first and second insulating interlayers
130 and 250, the insulation layers 110, and the sacrificial layers
120 may be formed to expose the upper surface of the substrate 100.
In an exemplary embodiment, the second opening 260 is formed by
performing an etching process using an etching mask. However,
exemplary embodiments of the present inventive concepts are not
limited thereto.
In an exemplary embodiment, the second opening 260 may extend in
the second direction, and a plurality of second openings 260 may be
formed along the third direction.
As the second opening 260 is formed, the insulation layer 110 may
be converted into an insulation pattern 115, and the sacrificial
layer 120 may be converted into a sacrificial pattern.
The sacrificial patterns exposed by the second opening 260 may be
removed to form a gap 270 between the insulation patterns 115 of
each level (e.g., in the first direction). A portion of an outer
sidewall of the preliminary first blocking pattern 175 and a
portion of a sidewall of the semiconductor pattern 150 may be
exposed by the gap 270. In an exemplary embodiment, the sacrificial
patterns exposed by the second opening 260 may be removed by a wet
etching process using an etchant including phosphoric acid or
sulfuric acid. However, exemplary embodiments of the present
inventive concepts are not limited thereto.
Referring to FIGS. 16 and 17, the preliminary first blocking
pattern 175 exposed by the gap 270 may be etched to expose an outer
sidewall (e.g., a sidewall farthest from the tunnel insulation
pattern 205 in the third direction) of the charge trapping layer
180. The exposed outer sidewall of the charge trapping layer 180
may be partially etched. Accordingly, the preliminary first
blocking pattern 175 may be converted into a first blocking pattern
177, and an upper portion and a lower portion of the charge
trapping layer 180 may be separated and converted into a charge
trapping pattern structure 185.
In an exemplary embodiment, the etching of the charge trapping
layer 180 may be performed by a wet etching process to selectively
etch nitride. Although the preliminary first blocking pattern 175
includes an oxide, the preliminary first blocking pattern 175 may
have a very small thickness, and thus may be removed by the etching
process. However, as a portion of the exposed preliminary first
blocking pattern 175 that contacts each of the insulation patterns
115 may have a large thickness in a direction in which the etching
process is performed, e.g., in the third direction, even though the
portion of the exposed preliminary first blocking pattern 175 is
partially removed by the etching process, portions may remain to
form the first blocking pattern 177. A surface of the first
blocking pattern 177 may be partially exposed by the gap 270.
In exemplary embodiments, a lowermost first blocking pattern 177 in
the first direction may partially cover each of a surface of the
insulation pattern 115 on the second level that may have the
greatest thickness (e.g., in the first direction) and the upper
surface of the semiconductor 150. An uppermost first blocking
pattern 177 in the first direction may partially cover a surface of
an uppermost insulation pattern 115 that may have a second greatest
thickness and a lower surface of the pad 240. For example, the
uppermost first blocking pattern 177 may cover a sidewall of the
insulation pattern 115 on the eighth level and a portion of the
lower surface of the pad 240. The first blocking pattern 177 on
remaining middle levels may partially cover surfaces of the
insulation patterns 115 on the remaining levels, respectively.
The etching process may be performed to remove the charge trapping
layer 180 until an outer sidewall of the tunnel insulation pattern
205 (e.g., the sidewall farthest from the channel 225 in the third
direction) may be partially exposed. Therefore, the charge trapping
layer 180 may be separated in the first direction by the exposed
outer sidewall of the tunnel insulation pattern 205 to form a
charge trapping pattern structure 185. The charge trapping pattern
structure 185 formed above (e.g., in the first direction) the
exposed outer sidewall of the tunnel insulation pattern 205 may be
referred to as an upper charge trapping pattern 185a, and the
charge trapping pattern structure 185 formed under (e.g., in the
first direction) the exposed outer sidewall of the tunnel
insulation pattern 205 may be referred to as a lower charge
trapping pattern 185b. The charge trapping pattern structure 185,
the tunnel insulation pattern 205 and the channel 225 altogether
may form a first structure. However, in other exemplary
embodiments, three or more separated charge trapping patterns may
be formed.
Each of the upper and lower charge trapping patterns 185a and 185b
may have a sidewall that is not vertical (e.g., perpendicular), but
varying with respect to the upper surface of the substrate 100
(e.g., extending in the third direction), and may have a
symmetrical shape along the first direction based on the exposed
outer sidewall of the tunnel insulation pattern 205. In an
exemplary embodiment, an upper surface of the upper charge trapping
pattern 185a contacting the first blocking pattern 177 and a lower
surface of the lower charge trapping pattern 185b contacting the
first blocking pattern 177 may have substantially the same width in
the third direction.
In an exemplary embodiment, the extent of etching of the charge
trapping layer 180 may be greater in portions that are closer to
each of the insulation patterns 115 in the first direction.
Accordingly, an outer sidewall of the upper charge trapping pattern
185a exposed by the gap 270 may have a slope that gradually
decreases toward the top, and an outer sidewall of the lower charge
trapping pattern 185b exposed by the gap 270 may have a slope that
gradually decreases toward the bottom.
In exemplary embodiments, a thickness of the upper charge trapping
pattern 185a in the third direction may gradually increase from the
top toward the bottom, and a thickness of the lower charge trapping
pattern 185b in the third direction may gradually decrease from the
top toward the bottom.
In an exemplary embodiment, the exposed outer sidewall of the
tunnel insulation pattern 205 may protrude from the channel 225 in
the third direction more than the exposed outer sidewall of the
charge trapping pattern structure 185. For example, as shown in the
exemplary embodiment of FIG. 16, the exposed outer sidewall of the
tunnel insulation pattern 205 may protrude greater from the channel
225 in the third direction than the exposed outer sidewall of the
charge trapping pattern structure 185 in a middle portion (e.g., in
the first direction) of the charge trapping pattern structure.
Referring to FIGS. 18 and 19, a second blocking layer 280 may be
formed to cover an inner wall of the gap 270 (e.g., a sidewall
adjacent the tunnel insulation pattern 205 and the lower surface
and upper surface of the insulation patterns 115), a sidewall of
the second opening 260, the upper surface of the substrate 100
exposed by the second opening 260, and an upper surface of the
second insulating interlayer 250.
The second blocking layer 280 may cover the exposed upper surface
of the substrate 100, a portion of the exposed sidewall of the
semiconductor pattern 150, the exposed surface of each of the
insulation patterns 115, the exposed surface of each of the first
blocking patterns 177, the exposed outer sidewall of each of the
charge trapping pattern structures 185, the exposed outer sidewall
of each of the tunnel insulation patterns 205, a sidewall of the
first insulating interlayer 130, and the upper surface of the
second insulating interlayer 250.
In an exemplary embodiment, the second blocking layer 280 may be
conformally formed to have a constant thickness, and may have a
greater thickness than the first blocking pattern 177.
In exemplary embodiments, corresponding to shapes of the outer
sidewall of the charge trapping pattern structure 185 and the outer
sidewall of the tunnel insulation pattern 205, a sidewall of the
second blocking layer 280 adjacent to the tunnel insulation pattern
205 between insulation patterns on upper and lower levels may have
a shape in which a central portion in the first direction protrudes
more than other portions along the third direction.
In the exemplary embodiment shown in FIG. 19, a lower surface
exposed by the gap 270 of an upper portion of the second blocking
layer 280 that contacts the insulation pattern 115 formed on the
upper level (hereinafter, referred to as an upper insulation
pattern 115) may be formed lower (e.g., in the first direction)
than a lower surface of the first blocking pattern 177 that
contacts the upper insulation pattern 115, and an upper surface
exposed by the gap 270 of a lower portion of the second blocking
layer 280 that contacts the lower insulation pattern 115 may be
formed higher (e.g., in the third direction) than an upper surface
of the first blocking pattern 177 that contacts the insulation
pattern 115 formed on the lower level (hereinafter, referred to as
a lower insulation pattern 115). In an exemplary embodiment, each
of the lower surface of the upper portion of the second blocking
layer 280 and the upper surface of the lower portion of the second
blocking layer 280 may have a slope substantially parallel to the
upper surface of the substrate 100.
In an exemplary embodiment, the second blocking layer 280 may have
the substantially same material as the first blocking pattern 177,
e.g., an oxide such as silicon oxide, and thus may be merged with
the first blocking pattern 177. However, exemplary embodiments of
the present inventive concepts are not limited thereto. For
example, in another exemplary embodiment, the second blocking layer
280 may have a structure in which a first layer including an oxide,
such as a silicon oxide, etc., and a second layer including a metal
oxide, such as aluminum oxide, hafnium oxide, zirconium oxide,
etc., are sequentially stacked.
Referring to FIGS. 20 and 21, a gate electrode layer may be formed
on the second blocking layer 280 to fill a remaining portion of the
gap 270.
In an exemplary embodiment, the gate electrode layer may include
agate barrier layer and a gate conductive layer sequentially
stacked. The gate conductive layer may include a metal having low
electrical resistance, e.g., tungsten, titanium, tantalum,
platinum, etc., and the gate barrier layer may include a metal
nitride, e.g., titanium nitride, tantalum nitride, etc. However,
exemplary embodiments of the present inventive concepts are not
limited thereto.
In an exemplary embodiment, an upper surface of the gate electrode
layer adjacent the upper insulation pattern 115 may be formed lower
than the lower surface of the first blocking pattern 177 that
contacts the upper insulation pattern 115 in the first direction,
and a lower surface of the gate electrode layer adjacent the lower
insulation pattern 115 may be formed higher than the upper surface
of the first blocking pattern 177 that contacts the lower
insulation pattern 115 in the first direction. Each of the upper
and lower surfaces of the gate electrode layer may have a slope
substantially parallel to the upper surface of the substrate 100
(e.g., extending in the third direction).
The gate electrode layer may be partially removed to form a gate
conductive pattern and a gate barrier pattern in the gap 270, and
the gate conductive pattern and the gate barrier pattern altogether
may form a gate electrode. In an exemplary embodiment, the gate
conductive pattern and the gate barrier pattern may be partially
removed by a wet etching process.
The gate electrode may extend in the second direction, and a
plurality of gate electrodes may be formed along the third
direction. For example, the plurality of gate electrodes extending
in the second direction may be spaced apart from each other in the
third direction by the second opening 260.
The gate electrode may include first to third gate electrodes 293,
295 and 297 sequentially formed along the first direction.
In an exemplary embodiment, an upper surface of the gate electrode
adjacent to the upper insulation pattern 115 may be formed lower
than the lower surface of the first blocking pattern 177 that
contacts the upper insulation pattern 115. A lower surface of the
gate electrode adjacent to the lower insulation pattern 115 may be
formed higher than the upper surface of the first blocking pattern
177 that contacts the lower insulation pattern 115. Each of the
upper and lower surfaces of the gate electrode may have a slope
substantially parallel to the upper surface of the substrate 100
(e.g., extending in the third direction).
In an exemplary embodiment, a central portion (e.g., in the first
direction) of a sidewall of the gate electrode contacting the outer
sidewall of the second blocking layer 280 between the upper and
lower insulation patterns 115 and being adjacent to the channel 225
(e.g., with the tunnel insulation pattern 205 and charge trapping
pattern 185 therebetween) may have a shape that is concave toward
the channel 225 compared to other portions of the sidewall of the
gate electrode. For example, the central portion of the sidewall of
the gate electrode may protrude further away from the channel 225
compared to the other portions.
In exemplary embodiments, the upper and lower charge trapping
patterns 185a and 185b may be formed on a space between each of the
second and third gate electrodes 295 and 297 and the tunnel
insulation pattern 205. The upper surface of the upper charge
trapping pattern 185a may be higher (e.g., in the third direction)
than upper surfaces of the second and third gate electrodes 295 and
297 adjacent thereto. A lower surface of the lower charge trapping
pattern 185b may be lower than lower surfaces of the second and
third gate electrodes 295 and 297 adjacent thereto.
Impurities may be injected into the exposed upper portion of the
substrate 100 to form an impurity region 105. A second spacer layer
may then be formed on an upper surface of the impurity region 105,
the sidewall of the second opening 260 and the upper surface of the
second insulating interlayer 250. The second spacer layer may be
anisotropically etched to form a second spacer 300 on the sidewall
of the second opening 260. Therefore, the impurity region 105 on
the upper portion of the substrate 100 may be partially
exposed.
The impurities may include n-type impurities, such as phosphorous,
arsenic, etc., and the second spacer layer may include an oxide,
such as silicon oxide, etc.
A CSL 310 may be formed on the exposed impurity region 105 to fill
a remaining portion of the second opening 260.
In exemplary embodiments, the CSL 310 may be formed by forming a
conductive layer on the exposed impurity region 105, the second
spacer 300 and the second insulating interlayer 250 to fill the
second opening 260. An upper portion of the conductive layer may
then be planarized until the upper surface of the second insulating
interlayer 250 is exposed. A portion of the second blocking layer
280 formed on the upper surface of the second insulating interlayer
250 may be also removed. Therefore, the second blocking layer 280
may be converted into a second blocking pattern 285. In an
exemplary embodiment, the conductive layer may include a metal, a
metal nitride and/or a metal silicide.
Referring to FIGS. 1 to 3 again, after forming a third insulating
interlayer 320 on the second insulating interlayer 250, the CSL
310, the second spacer 300 and the second blocking pattern 285, a
contact plug 330 extending through the third insulating interlayer
320 and the second insulating interlayer 250 and contacting an
upper surface of the pad 240 may be formed.
A fourth insulating interlayer 340 may be formed on the third
insulating interlayer 320 and the contact plug 330. A bit line 350
that extends through the fourth insulating interlayer 340 and
contacts an upper surface of the contact plug 330 may be formed to
complete the fabrication of the vertical memory device.
The third and fourth insulating interlayers 320 and 340 may include
oxide, such as silicon oxide, etc., and the contact plug 330 and
the bit line 350 may include a metal, such as copper, aluminum,
tungsten, titanium, tantalum, etc., and/or a metal nitride, such
as, titanium nitride, tantalum nitride, tungsten nitride, etc.
In an exemplary embodiment, the bit line 350 may extend in the
third direction, and a plurality of bit lines may be arranged along
the second direction.
As described above, the charge trapping pattern structure 185
formed between each of the second to third gate electrodes 295 and
297 among the gate electrodes and the channel 225 may include the
upper and lower charge trapping patterns 185a and 185b spaced apart
from each other along the first direction. A plurality of charge
trapping patterns may be arranged in one transistor. Therefore, the
degree of integration of the vertical memory device including the
transistor may be increased. Additionally, electrons may be
efficiently injected into the second to third gate electrodes 295
and 297 through each of the upper and lower charge trapping
patterns 185a and 185b, and thus the electrical characteristic of
the vertical memory device may be improved.
As the second to third gate electrodes 295 and 297 and the
insulation patterns 115 may be formed to have a concave-convex
shape in the first direction as a whole, the charge trapping
pattern structure 185 may be at least partially interposed between
the second to third gate electrodes 295 and 297 along the first
direction, so that the interference between neighboring second or
third gate electrodes 295 and 297 may be minimized. Therefore,
coupling between the second electrodes 295 serving as word lines
may be reduced.
FIGS. 22 and 23 are cross-sectional views illustrating stages of a
method of manufacturing a vertical memory device in accordance with
exemplary embodiments of the present inventive concepts. FIGS. 22
and 23 are cross-sectional views taken along the line A-A' of FIG.
1.
The method of manufacturing the vertical memory device includes
processes substantially the same as or similar to the processes
described in FIGS. 4 to 21 and FIGS. 1 to 3. Thus, detailed
descriptions thereon are omitted herein.
Referring to FIG. 22, processes substantially the same as or
similar to the processes described in FIGS. 4 to 6 may be
performed.
However, before forming the semiconductor pattern 150, sidewalls of
the sacrificial layers exposed by the channel hole 140 may be
partially removed to form the first recesses 160.
Accordingly, the first recesses 160 may be formed on all of the
sacrificial layers 120 including the lowermost sacrificial layer,
and the semiconductor pattern 150 may be formed to fill the first
recess 160 that may be formed on the lowermost sacrificial layer
120.
An upper portion and a lower portion of the semiconductor pattern
150 may have substantially the same width. However, at least a
central portion may have a greater width than each of the upper and
lower portions. Therefore a sidewall of semiconductor pattern 150
may have a shape in which a central portion in the first direction
protrudes further toward the sacrificial layers 120 compared to
other portions. For example, the central portion of the sidewalls
of the semiconductor pattern 150 may protrude further toward the
sacrificial layers 120 in an amount equal to a width of the first
recesses 160. In an exemplary embodiment, an air gap may be formed
on the central portion of the semiconductor pattern 150.
Referring to FIG. 23, processes substantially the same as or
similar to the processes described in FIGS. 8 to 21 and FIGS. 1 to
3 may be performed to complete the fabrication of the vertical
memory device.
FIGS. 24 and 25 are cross-sectional views illustrating stages of a
method of manufacturing a vertical memory device in accordance with
exemplary embodiments of the present inventive concepts. FIG. 24 is
a cross-sectional view taken along the line A-A' of FIG. 1, and
FIG. 25 is an enlarged cross-sectional view of a region X in a
corresponding cross-sectional view.
The method of manufacturing the vertical memory device includes
processes substantially the same as or similar to the processes
described in FIGS. 4 to 21 and FIGS. 1 to 3. Thus, detailed
descriptions thereon are omitted herein.
Referring to FIGS. 24 and 25, the vertical memory device may
further include a third blocking pattern 289 formed between the
second blocking pattern 285 and the gate electrode 297. The third
blocking pattern 289 may cover the gate electrode, upper and lower
surfaces of the gate electrode, and one sidewall of the gate
electrode.
In an exemplary embodiment, the third blocking pattern 289 may be
also formed between the second blocking pattern 285 and the second
spacer 300.
In an exemplary embodiment, the third blocking pattern 289 may be
conformally formed to have a constant thickness. In an exemplary
embodiment, a thickness of the third blocking pattern 289 may be
substantially the same as a thickness of the second blocking
pattern 285, and may be greater than a thickness of the first
blocking pattern 177.
The third blocking pattern 289 may include a metal oxide, such as
aluminum oxide, hafnium oxide, zirconium oxide, etc.
FIGS. 26 and 27 are cross-sectional views illustrating stages of a
method of manufacturing a vertical memory device in accordance with
an exemplary embodiment of the present inventive concepts. FIG. 26
is an enlarged cross-sectional view of the region X in FIG. 2, and
FIG. 27 is an enlarged cross-sectional view of the region X in FIG.
2.
The method of manufacturing the vertical memory device includes
processes substantially the same as or similar to the processes
described in FIGS. 4 to 21 and FIGS. 1 to 3. Thus, detailed
descriptions thereon are omitted herein.
Referring to FIG. 26, processes substantially the same as or
similar to the processes described in FIGS. 4 to 17 may be
performed.
However, when etching the preliminary first blocking pattern 175
exposed by the gap 270 to expose the outer sidewall of the charge
trapping layer 180, and then partially etching the exposed outer
sidewall of the charge trapping layer 180 to form the first
blocking pattern 177 and the charge trapping pattern structure 185,
the etching process may be performed to a greater extent on a
central portion in the first direction than other portions of the
outer sidewall of the charge trapping layer 180. Therefore, the
charge pattern structure may be etched to a greater extent as the
charge pattern structure gets closer to a portion of the outer
sidewall of the tunnel insulation pattern 205 that has a shape more
protruding from the channel 225 along the third direction. For
example, the charge pattern structure 185 may be etched to a
greater extent as it gets closer to the middle portion of the
charge pattern structure in the first direction.
In an exemplary embodiment, the outer sidewall of the tunnel
insulation pattern 205 may protrude from the channel 225 along the
third direction more than a lower portion of the outer sidewall of
the upper charge trapping pattern 185a and an upper portion of the
outer sidewall of the lower charge trapping pattern 185b.
In an exemplary embodiment, the outer sidewall of the upper charge
trapping pattern 185a may have a slope that decreases toward the
top, and the outer sidewall of the lower charge trapping pattern
185b may have a slope that decreases toward the bottom.
Referring to FIG. 27, processes substantially the same as or
similar to the processes described in FIGS. 18 to 21 and FIGS. 1 to
3 may be performed to complete the fabrication of the vertical
memory device.
The sidewall of the second blocking pattern 285 adjacent to the
channel 225, and the sidewalls of each of the second and third gate
electrodes 295 and 297 adjacent to the channel 225 may have shapes
corresponding to the outer sidewall of the tunnel insulation
pattern 205, and the outer sidewall of the charge trapping pattern
structure 185. For example, the middle portions (e.g., in the first
direction) of the second blocking pattern 285, second electrodes
295 and third electrodes 297 may have a concave shape in the third
direction toward the channel 225.
FIGS. 28 and 29 are cross-sectional views illustrating stages of a
method of manufacturing a vertical memory device in accordance with
exemplary embodiments of the present inventive concepts. FIG. 28 is
an enlarged cross-sectional view of the region X in FIG. 20. FIG.
29 is an enlarged cross-sectional view of the region X in FIG.
2.
The method of manufacturing the vertical memory device includes
processes substantially the same as or similar to the processes
described in FIGS. 4 to 21 and FIGS. 1 to 3. Thus, detailed
descriptions thereon are omitted herein.
Referring to FIG. 28, processes substantially the same as or
similar to the processes described in FIGS. 4 to 17 may be
performed.
However, when etching the preliminary first blocking pattern 175
exposed by the gap 270 to expose the outer sidewall of the charge
trapping layer 180, and then partially etching the exposed outer
sidewall of the charge trapping layer 180 to form the first
blocking pattern 177 and the charge trapping pattern structure 185,
the etching process may be performed to a greater extent on an
upper portion, a lower portion and a central portion in the first
direction of the charge trapping layer 180. The etching process may
be performed to a lesser extent on each of a first portion of the
outer sidewall of the upper charge trapping pattern 185a disposed
between an upper portion and a lower portion thereof and a second
portion of the outer sidewall of the lower charge trapping pattern
185b disposed between an upper portion and a lower portion thereof.
Therefore, the charge trapping pattern structure 185 including the
upper and lower charge trapping patterns 185a and 185b may have a
curved shape as a whole.
In an exemplary embodiment, the outer sidewall (e.g., a sidewall
farthest from the channel 225) of the tunnel insulation pattern 205
may protrude from the channel 225 along the third direction more
than each of the upper portion and the lower portion of the outer
sidewall of the upper charge trapping pattern 185a, and each of the
upper portion and the lower portion of the outer sidewall of the
lower charge trapping pattern 185b. However, in other exemplary
embodiments, the outer sidewall of the tunnel insulation pattern
205 may protrude less than the first portion of the upper charge
trapping pattern 185a and the second portion of the lower charge
trapping pattern 185b. In the exemplary embodiment shown in FIG.
28, the outer sidewall of the tunnel insulation pattern protrudes
to a substantially same point in the third direction as the
protrusions of the upper charge trapping pattern 185a and lower
charge trapping pattern 185b.
In an exemplary embodiment, the outer sidewall of the charge
trapping pattern structure 185 may have a slope that is not
vertical (e.g., perpendicular) but varies (e.g., extends in the
third direction) with respect to the upper surface of the substrate
100.
In an exemplary embodiment, a thickness of the upper charge
trapping pattern 185a in the third direction may be greatest at the
first portion of the upper charge trapping pattern 185a, and a
thickness of the lower charge trapping pattern 185b in the third
direction may be greatest at the second portion of the lower charge
trapping pattern 185b.
Referring to FIG. 29, processes substantially the same as or
similar to the processes described in FIGS. 18 to 21 and FIGS. 1 to
3 may be performed to complete the fabrication of the vertical
memory device.
The sidewall of the second blocking pattern 285 adjacent to the
channel 225, and the sidewalls of each of the second and third gate
electrodes 295 and 297 adjacent to the channel 225 may have shapes
corresponding to the outer sidewall of the tunnel insulation
pattern 205, and the outer sidewall of the charge trapping pattern
structure 185.
For example, the sidewall of the second blocking pattern 285 and
the sidewalls of each of the second and third gate electrodes 295
and 297 may have slopes that are not vertical (e.g.,
perpendicular), but varying (e.g., extending in the third
direction) with respect to the upper surface of the substrate 100,
respectively.
In exemplary embodiments, the sidewalls of each of the second and
third gate electrodes 295 and 297 adjacent to the channel 225 in
the third direction may have a wave shape toward the channel 225 as
a whole.
As described above, although the present invention has been
described with reference to exemplary embodiments, those skilled in
the art will readily appreciate that many modifications are
possible in the exemplary embodiments without materially departing
from the novel teachings and advantages of the present inventive
concepts.
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